Renovations in Chiswick

Look along a Chiswick roofline from Turnham Green and much of what you see is not a simple pitched roof at all. Behind the parapets of the W4 terraces sit butterfly roofs, two slopes falling inwards to a central valley gutter that has to carry water the length of the house before discharging at the back. That single detail explains a large share of the problems we are called to in Chiswick, and it changes what a loft conversion or a top floor renovation involves. GS Renovation works across the postcode on structural, extension and refurbishment projects, coordinating Hounslow Council building control.

Valley gutters, parapets and the top of the house

A central valley gutter has no margin for neglect. Debris collects, the outlet blocks, water backs up over the upstand and finds its way into the roof timbers and the top floor ceilings, and because it is invisible from the street it can go on for years. Parapet walls add their own contribution, since old copings and failed flashings let water into brickwork that then sheds its face in frost. We survey the whole assembly rather than patching the spot where the stain has appeared. Relining a valley properly is a short job, while ignoring it costs a ceiling.

That roof form also governs what can be done above the top floor. Converting a loft under a butterfly roof usually means a mansard or a rear extension of the roof rather than a straightforward dormer, and it always means resolving the valley and the rainwater route as part of the design. Where the roof is being reformed, the structural engineer designs the new members and their bearings into the party walls, and building control inspects the structure and the weathering before anything is lined out. Rainwater disposal is designed at the same time, not added later.

Below stairs: lower ground floors and pavement vaults

The taller W4 terraces off the High Road often include a basement level opening onto a front lightwell, with vaults reaching out under the pavement. Renovating that level is popular and entirely achievable, but it starts with the condition of the vault and the drainage, not with the kitchen layout. Old salt glazed drains, a lightwell gully that overflows in heavy rain and brickwork softened by decades of standing water are all common, and all need dealing with before finishes go in. Old drainage is tested before a new floor is laid over it.

Where more headroom is wanted, lowering a floor is a structural operation and not a matter of digging out a bit at a time. Existing foundations may need underpinning in designed sequence, and the retaining condition against the street has to be considered. The engineer we appoint produces that design and we build to it in bays, with building control inspecting as the sequence progresses. Party wall notices are served before excavation near a shared boundary begins. Excavating a lower ground floor without that design is how a front elevation ends up moving.

Where most Chiswick projects start: whole-house refurbishment in Chiswick, everything we cover across Hounslow, renovations in Brentford, renovations in Isleworth and building regulations explained.